Implosion is a shooter in which a planet is on full collision course towards the earth. Now the player has to infiltrate said planet to let it implode. In every level big energy balls have to be destroyed to weaken the planet's defenses. When all are gone, a portal opens up which has to be entered within ten seconds - it is unhealthy to stay.
Also unhealthy are the enemies which attack frontally. If they manage to touch the ship its energy goes down and zero energy results in a life loss. Fortunately the player can shoot them and also destroy special crystals. Those split up into smaller crystals which reward more energy, better shields or extra points when picked up.